Fedora 21 Update: glibc-2.20-5.fc21

[updates at fedoraproject.org]

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Fedora Update Notification
FEDORA-2014-11673
2014-09-27 08:47:55
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Name        : glibc
Product     : Fedora 21
Version     : 2.20
Release     : 5.fc21
URL         : http://www.gnu.org/software/glibc/
Summary     : The GNU libc libraries
Description :
The glibc package contains standard libraries which are used by
multiple programs on the system. In order to save disk space and
memory, as well as to make upgrading easier, common system code is
kept in one place and shared between programs. This particular package
contains the most important sets of shared libraries: the standard C
library and the standard math library. Without these two libraries, a
Linux system will not function.

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Update Information:

Update glibc at the same time or before upgrading microcode_ctl on Intel Haswell hardware that has hardware transactional memory support. If you upgrade microcode_ctl before upgrading glibc your system will fail to boot and you will need to rescue your system (downgrade microcode_ctl).

Intel errata HSW136 identifies a defect in hardware transactional memory support that requires the user to install a new microcode update to disable this cpu feature. Unfortunately the present method for updating microcode (microcode_ctl) happens too late in the system boot order causing all already running threads that use this feature to die with invalid opcode errors. In order to prevent users from damaging their systems this glibc update completely disables hardware transactional memory support in POSIX threads for Intel devices until such a time as the microcode update can be done earlier in the boot process.
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References:

  [ 1 ] Bug #1146967 - Latest firmware update causes SIGILL on xbeginq instruction on Haswell processors
        https://bugzilla.redhat.com/show_bug.cgi?id=1146967
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This update can be installed with the "yum" update program.  Use
su -c 'yum update glibc' at the command line.
For more information, refer to "Managing Software with yum",
available at http://docs.fedoraproject.org/yum/.

All packages are signed with the Fedora Project GPG key.  More details on the
GPG keys used by the Fedora Project can be found at
https://fedoraproject.org/keys
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